The Ecology and Conservation of Thestorbrachycerusbrachycerus (Trimen, 1883) An

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The ecology and conservation of Thestorbrachycerusbrachycerus (Trimen, 1883) – an aphytophagousmiletine butterfly from South Africa

Liz A Bazin1, David A Edge2

North-West University, Potchefstroom, North-West Province, South Africa.

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2 (corresponding author)

Appendix 1 – Habitat description

General area

The study area is situated to the east of the Eastern Heads at Knysna (Figure 1). The underlying geology is the Peninsula Formation of the Table Mountain Group - quartz sandstones of Ordovician age, overlain at the Pezula study site by aeolian sands of late Pleistocene age (Toerien 1979). The climate (Edge 2005b) is Köppen classification Cfa (Schultze and McGee 1978), with mean annual precipitation (MAP) of 750mm, and rainfall in all months, peaking in spring and autumn. Daily maximum and minimum temperatures average 23.3°C and 12.5°C respectively, and the relative humidity averages a high 88%. Prevailing winds are south-easterly during summer and south-westerly during winter, with occasional northerly winds which cause a severe lowering of humidity and increased fire hazard.

Pezula study site

For location and altitude see Table 1. The site is on a north-west facing slope with an inclination varying between 10 and 15 degrees (12.5° average). The substrate is medium grained acidic to neutral regic sands (Mucina and Rutherford 2006; Fey 2010) with occasional rocky outcrops. The vegetation was classified byMucina and Rutherford (2006:671–2) as Knysna Sand Fynbos (FFd 10), a Critically Endangered vegetation type with almost 70% already transformed and only 5% conserved (Rouget et al 2006). Important taxa mentioned by Mucina and Rutherford (2006) that have been recorded on the site are Metalasiadensa, Anthospermumaethiopicum, Erica sessiliflora, Leucadendronsalignum, Seriphiumplumosum, Eragrostiscapensis, Ficiniabulbosa, Heteropogoncontortus, Ischyrolepiseleocharis, Thamnocortuscinereus, andTristachyaleucothrix. The vegetation has been transformed to some extent by past agricultural practices (e.g. low intensity cattle grazing) and artificial fire regimes (too regular burns to promote grazing in earlier years and then exclusion of fire since the mid-1990s) (Edge 2005a).

Coastal study site

For location and altitude see Table 1. The sites are on fairly level ground with the highest spring tide mark only 5m to the south. The study site is situated on a littoral terrace (the Swartkops horizon) formed during the Pleistocene around 40–45 000 years ago (Butzer and Helgren 1972). The extant substrate consists of a jumble of rocky boulders and stones with thin soil cover in places.

The abiotic conditions are severe with high salt deposition (exposure to salt spray and seawater splash), extremely high insolation, and high levels of UV radiation. Nutrient input by birds, and constant deposition and erosion of fine soil by relentless winds are ecologically critical (Mucina and Rutherford 2006).

The vegetation was classified byMucina and Rutherford (2006:685–6) as Cape Seashore Vegetation (AZd 3). The study site is the south coast variant (Lubke 1998) with rocky marine shelves below rocky cliffs. Important taxa mentioned by Mucina and Rutherford (2006) that have been recorded on the site are Pelargonium capitatum, Tetragoniadecumbens, Gazaniarigens, Carpobrotusedulis, Limoniumsp. nov.andLobelia anceps. The site has been traversed regularly by fishermen and this has caused some littering; otherwise it is in natural condition.

References

Butzer KW, Helgren, DM (1972) Late Cenozoic evolution of the Cape Coast between Knysna and Cape St. Francis, South Africa.Quat Res 2:143–169

Edge DA (2005a) Butterfly conservation in the southern Cape. Metamorphosis 16:28–46

Edge DA (2005b) Ecological factors influencing the survival of the Brenton Blue butterfly, Orachrysopsniobe (Trimen) (Lepidoptera: Lycaenidae). Potchefstroom: North-West University. (Thesis - D.Phil.) 265 p

Fey M (2010) Soils of South Africa.Cambridge University Press. Cambridge.

Lubke RA (1998) The coastal environment. In: Lubke RA, de Moore I (eds)Field guide to the eastern and southern Cape coasts, UCT Press, Cape Town

Mucina L, Rutherford MC (2006) The Vegetation of South African, Lesotho and Swaziland, Strelitzia 19. South African National Biodiversity Institute, Pretoria

Rouget M, Jonas Z, Cowling RM, Desmet PG, Driver A, Mohamed B, Mucina L, Rutherford MC, Powrie LW (2006) Ecosystem status and protection levels of vegetation types. In: Mucina L, Rutherford MC (eds) The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria, pp 724–737

Schulze RE, McGee OS (1978) Climatic indices and classifications in relation to the biogeography of southern Africa. In Werger MJA (ed)Biogeography and ecology of southern Africa, W. Junk, The Hague pp 19–55

Toerien DK (1979) The geology of the Oudtshoorn area. Explanation to sheet 3322. Government Printer, Pretoria.

Appendix 2 – Most abundant plant taxa

Top twentymost abundant plant taxa, with family and average height, recorded during vegetation surveys carried out at the Pezula site in December 2011 and at the coastal site in March 2014. Taxa are listed in order of abundance (greatest to smallest).

Appendix 3 – Vegetation structure

Vegetation structure of all the relevés at the Pezula and Coastal study sites, showing total cover of all plants (sum of midpoints), the percentage bare ground, rocks and dead plant matter, and the presence (+) or absence (-) of Anoplolepiscustodiensdetermined from pitfall trap sampling, or detected by hand sampling (h), and the presence (+) or absence (-) of Thestor b. brachycerusdetermined by the relevés within the P1 and C1 colonies.

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